Reinforced balloon catheter

ABSTRACT

A balloon catheter is described having a reinforced, co-axial, duel lumen design. In some embodiments, the balloon catheter includes a purging mechanism designed to purge air from the balloon.

RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application Serial No.16/940,205 filed Jul. 27, 2020 entitled Improved Reinforced BalloonCatheter, which is a continuation of and claims priority to U.S. Pat.Application Serial No. 15/605,820 filed May 25, 2017 entitled ImprovedReinforced Balloon Catheter (now Pat. No. 10,786,659 Issued Sep. 29,2020), which claims benefit of and priority to U.S. ProvisionalApplication Serial No. 62/344,371 filed Jun. 1, 2016 entitled ReinforcedBalloon Catheter, and to U.S. Provisional Application Serial No.62/380,979 filed Aug. 29, 2016 entitled Porosity Purging System forCatheter, all of which are hereby incorporated herein by reference intheir entireties.

FIELD OF THE INVENTION

The present invention relates to balloon catheters and, moreparticularly, to balloon catheters for use in neurological procedures.

BACKGROUND OF THE INVENTION

Balloon catheters are increasingly being employed to conductneurological procedures in patients. However, the design parameters forballoon catheters intended for use in neurological procedures aresignificantly different than the design parameters for balloon cathetersused in non-neurological procedures such as cardiological procedures.For example, the width of the circulatory system within the neuroanatomyis significantly smaller and more tortuous than the circulatory systemin other parts of the body. In order to access the smaller and moretortuous regions of the neuroanatomy, it is necessary to minimize theouter diameter of the balloon catheter while simultaneously maintainingthe pushability and trackability of the catheter.

Balloon catheters and balloons for neurovasculature use offer particulardesign complications given the small design profile. Balloon cathetersoften utilize a purging system to purge residual air from the ballooncatheter prior to placement in the vasculature. However, purging systemsstill may leave an escape path for the balloon inflation media resultingin the balloon deflating in the vasculature. This is of special concernfor neurovascular balloons, since such balloons are particularly smallany minimal leakage can lead to balloon deflation which can negativelyimpact the intravascular procedure. Additionally, proper dispensation ofinflation media is important to avoid overfilling or underfilling theballoon - this is especially critical with neurovascular balloons giventhe small size of the balloon.

The present invention addresses these and other issues by utilizing apurging system for a balloon catheter which does not lead to balloondeflation and utilizing metered dispensation for precise filling of theballoon with inflation media.

OBJECTS AND SUMMARY OF THE INVENTION

In one embodiment, the present invention includes a balloon catheterthat is operable to use with large gauge guidewires, resists ovalizingand kinking of the inflation and guidewire lumen(s), and deploys withimproved pushability and trackability.

The present invention according to another embodiment provides a ballooncatheter that employs a reinforced, co-axial, duel lumen design. Incertain embodiments, the lumens are formed of a multilayer, tubularelement in which one of the layers functions, in part, to provide radialreinforcement to the tubular element.

In another embodiment of the present invention, the distal portion of anouter lumen is locked or fixed to a portion of an inner lumen. Aproximal portion of a balloon is attached to a distal portion of theouter lumen and a distal portion of the balloon is attached to a distalportion of the inner lumen.

In another embodiment, a fluid flow passage is provided between theouter lumen and an interior volume of the balloon, and a passageexclusive to gas or air is formed from the interior volume of theballoon longitudinally through a distal portion of the balloon catheter.

In certain other embodiments, de-airing channels or features areemployed between an exterior surface of the inner lumen and an interiorsurface of the balloon in order to facilitate purging of gas from theinflation passageway of the balloon catheter.

In other embodiments, leak-proofing systems can be included to mitigateor prevent the balloon from leaking and deflating during operation.

In another embodiment, a tapered inflation lumen is utilized. In anotherembodiment, a tapered guidewire lumen is utilized. In anotherembodiment, both the inflation lumen and guidewire lumen are tapered.The taper can be continuous throughout the lumen(s), or localized withina particular region of the lumen(s).

In another embodiment, a balloon catheter includes a membrane whichselectively allows the passage of air but retains liquid. The use ofthis membrane can be beneficial for prepping a balloon catheter for use,where air is purged from the balloon before it is placed in thepatient’s vasculature.

In another embodiment, a syringe which allows metered dispensing ofinflation media to a balloon in a balloon catheter is provided.

In another embodiment, a balloon catheter system includes a syringewhich allows metered dispensing of inflation media and a membrane whichselectively allows the passage of air but retains liquid, therebyallowing the user to purge air from the balloon but retain the inflationmedia within the balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 is an elevation view of a balloon catheter according to oneembodiment of the present invention.

FIG. 2 is a partial elevation view of a balloon catheter according toone embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1 of aballoon catheter according to one embodiment of the present invention.

FIG. 4A is a partial elevation view of an outer assembly of a ballooncatheter according to one embodiment of the present invention.

FIG. 4B is a cross-sectional view taken along line C-C of FIG. 4A of anouter assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 5A is a partial elevation view of an inner assembly of a ballooncatheter according to one embodiment of the present invention.

FIG. 5B is a cross-sectional view taken along line D-D of FIG. 5A of aninner assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 5C is a cross-sectional view taken along line E-E of FIG. 5A of aninner assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 6 is an expanded view of region 13 indicated in FIG. 1 of a ballooncatheter according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along line B-B of FIG. 2 of aninner assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 8 is a cross-sectional view taken along line D-D of FIG. 5A of aninner assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 9 is a cross-sectional view taken along line B-B of FIG. 2 of aninner assembly of a balloon catheter according to one embodiment of thepresent invention.

FIG. 10 is a cross-sectional view of a balloon catheter with acollapsible purge port according to one embodiment of the presentinvention.

FIG. 11 is a cross-sectional view of a collapsible purge port in an openconfiguration according to one embodiment of the present invention.

FIG. 12 is a cross-sectional view of a collapsible purge port in aclosed configuration according to one embodiment of the presentinvention.

FIG. 13 is a cross-sectional view of a balloon catheter utilizing a bumpto prevent access to a purge port according to one embodiment of thepresent invention, where the balloon is inflated.

FIG. 14 is a cross-sectional view of a balloon catheter utilizing a bumpto prevent access to a purge port according to one embodiment of thepresent invention, where the balloon is deflated.

FIG. 15 is a cross-sectional view of a balloon catheter with a closablepurge port and a bump according to one embodiment of the presentinvention, where a balloon is inflated.

FIG. 16 is a cross-sectional view of a balloon catheter with a closablepurge port and a bump according to one embodiment of the presentinvention, where a balloon is deflated.

FIG. 17 is a cross-sectional view of a portion of a balloon catheterwith a permeable membrane according to one embodiment of the presentinvention.

FIG. 18 is a cross-sectional view along line F of FIG. 17 of a ballooncatheter with a permeable membrane according to one embodiment of thepresent invention.

FIG. 19 a is a longitudinal view of a portion of a linearly taperedouter lumen of a balloon catheter according to one embodiment of thepresent invention.

FIG. 19 b is a longitudinal view of a portion of a non-linearly taperedouter lumen of a balloon catheter according to one embodiment of thepresent invention.

FIG. 19 c is a longitudinal view of a portion of a balloon catheterutilizing a localized inner and outer lumen taper according to oneembodiment of the present invention.

FIG. 20 a is an elevation view of a metered dispenser delivery systemincluding a metered controller according to one embodiment of thepresent invention.

FIG. 20 b is an elevation view of the metered dispenser delivery systemof FIG. 20 a including a metered controller according to one embodimentof the present invention.

FIG. 20 c is a partial elevation view of a metered controller used inthe metered dispenser delivery system of FIGS. 20 a and 20 b accordingto one embodiment of the present invention, where a protruding elementis not aligned with a groove.

FIG. 20 d is a partial elevation view of a metered controller used inthe metered dispenser delivery system of FIGS. 20 a and 20 b accordingto one embodiment of the present invention, where a protruding elementis aligned with a groove.

FIG. 20 e is an exploded view of the metered dispenser delivery systemof FIGS. 20 a-20 d according to one embodiment of the present invention.

FIG. 21 a is an exploded view of a metered dispenser system where ametered controller includes a top piece which sits over a bottom pieceaccording to one embodiment of the present invention.

FIG. 21 b is a perspective view of the metered dispenser system of FIG.21 a .

FIG. 22 a is an exploded view of a metered dispenser system utilizing ametered controller and a clamp according to one embodiment of thepresent invention.

FIG. 22 b is a perspective view of the metered dispenser system of FIG.22 a .

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

The balloon catheter of the present invention overcomes many of theshortcomings of the current balloon catheters intended for use inneurological procedures. Broadly speaking, the balloon catheter of thepresent invention employs a reinforced, co-axial, duel lumen design. Theinner most lumen is operable to serve, among other functions, as aguidewire lumen for over-the-wire type procedures. The outer lumen isoperable to serve as an inflation lumen for one or more balloonspositioned along the length of the balloon catheter. Each lumen isformed by a multilayer, tubular element in which one of the layers, forexample a middle layer in a three-layer embodiment, functions in part toprovide radial reinforcement to the tubular element. Accordingly, theballoon catheter of the present invention is operable with larger gaugeguidewires; resists ovalizing and kinking of the inflation and guidewirelumens; and deploys with improved pushability and trackability overcurrent balloon catheters intended for use in neurological procedures.

With reference to FIGS. 1-3 and 6 , a balloon catheter 10 according toone embodiment of the present invention comprises a hub 12, a balloon18, and an outer assembly 14 having a lumen 20 through which an innerassembly 16 is co-axially positioned. As best shown in FIG. 6 , anexpanded view of region 13 indicated in FIG. 1 , a proximal portion 36of the outer assembly 14 is associated with an inflation lumen 32 of thehub 12. A proximal portion 38 of the inner assembly 16 extendsproximally from the lumen 20 of the outer assembly 14 and is associatedwith a guidewire port 34 of the hub 12. At an opposite end of thecatheter, a proximal portion 24 of the balloon 18 is associated with adistal portion 26 of the outer assembly 14, and a distal portion 28 ofthe balloon 18 is associated with a distal portion 30 of the innerassembly 16. Alternatively stated, the opposite ends of the balloon 18span between the distal portion 26 of the outer assembly 14 and thedistal portion 30 of the inner assembly 16.

As shown in FIGS. 4A and 4B, the outer assembly 14 is a tubularstructure having a multilayer wall; an inner layer 40, a middle layer42, and an outer layer 44. The inner layer 40 of the outer assembly 14is formed of a longitudinally continuous or segmented tubular element.In embodiments in which the inner layer 40 of the outer assembly 14 isformed of longitudinally segmented tubular elements the individualsegments may be fabricated from the same or different materials and maybe attached to one another by welding, fusing, adhering, melting, orother polymerizing or non-polymerizing methods. The inner layer 40 ofthe outer assembly 14 is fabricated from one or more different polymericmaterials, or, alternatively, the inner layer 40 of the outer assembly14 is formed of a single etched polytetrafluoroethylene, PTFE, tube.While a variety of materials are contemplated for use in fabricating theinner layer 40 of the outer assembly 14, of particular importance is thefeature that the material from which the inner layer 40 is formed has ahigher melting temperature than the temperature employed to fuse orotherwise attach the outer layer 44 to the inner layer 40 and middlelayer 42 of the outer assembly 14.

In one embodiment of the present invention, the middle layer 42 of theouter assembly 14 comprises a wire 46 wound in a coil-like form aroundthe outer surface 48 of the inner layer 40 of the outer assembly 14. Thewire 46 may be wound in a single layer from one end of the inner layer40 to the other end to form a coil-like structure or, alternatively, maybe wound repeatedly from one end of the inner layer 40 to the other endto form a multilayer coil-like form, as shown in FIG. 4A. In embodimentsemploying the middle layer 42 having a multilayered coil-like form, thedifferent windings may be formed from a single or multiple independentwires 46. The wire 46 may have a circular, rectangular, triangular, orflattened ribbon-like cross-sectional shape, or combinations thereof.The wire 46 is fabricated from a variety of polymeric and/or metallicmaterials, for example stainless steel. The wire 72 has a diameter thatis variable or consistent along the length of the wire 72. For example,the wire 72 may have a diameter of approximately 0.001 inches. It isalso contemplated that the middle layer 42 be formed of a mesh, a braid,and/or an interweaving of one of more wires 46.

The pitch of the winding of the wire 46 may be either consistent orvaried along the length of the inner layer 40. For example, a firstproximal segment of the winding may have a pitch of approximately 0.003inches, a second more distal segment may have a pitch of approximately0.0035 inches, a third more distal segment may have a pitch ofapproximately 0.004 inches, a fourth more distal segment may have apitch of approximately 0.0045 inches, a fifth more distal segment mayhave a pitch of approximately 0.005 inches, and a sixth more distalsegment may have a pitch of approximately 0.001 inches. In embodimentsemploying the middle layer 42 having a multilayered coil-like form theouter most winding may, for example, have a pitch of approximately 0.100inches.

In one embodiment of the present invention, the outer layer 44 of theouter assembly 14 comprises a longitudinally continuous or segmentedtubular element. The outer layer 44 of the outer assembly 14 is formedof longitudinally segmented, non-heat shrinkable, tubular elements. Theindividual segments may be fabricated from the same or differentmaterials and may be attached to one another by welding, fusing,adhering, melting, or other polymerizing or non-polymerizing methods, orcombinations thereof.

In one embodiment, the outer layer 44 of the outer assembly 14 isfabricated from multiple different polymeric tubular segments. Forexample, a proximal segment 50 of the outer layer 44 of the outerassembly 14 may be formed of a tubular polyamide such as Grilamid L25.The proximal segment 50 has a length 51 of, for example, approximately110 centimeters. A second more distal segment 52 may be formed of atubular poly ether block amide such as Pebax 72D. The second more distalsegment 52 has a length 53 of, for example, approximately 10centimeters. A third more distal segment 54 may be formed of a tubularpoly ether block amide such as Pebax 63D. The third more distal segment54 has a length 55 of, for example, approximately 5 centimeters. A forthmore distal segment 56 may be formed of a tubular poly ether block amidesuch as Pebax 55D. The forth more distal segment 56 has a length 57 of,for example, approximately 20 centimeters. A fifth more distal segment58 may be formed of a tubular poly ether block amide such as Pebax 45D.The fifth more distal segment 58 has a length 59 of, for example,approximately 10 millimeters. A sixth more distal segment 60 may beformed of a polyolefin such a Plexar. The sixth more distal segment 60has a length 61 of, for example, approximately 2 millimeters. A distalmost segment 62 may be formed of a polyolefin such an Engage 8003. Thedistal most segment 62 has a length 63 of, for example, approximately 13centimeters.

The outer assembly 14 may be fabricated by first wrapping the wire 46around the inner layer 40 thereby forming the middle layer 44. Thetubular segment or segments of the outer layer 44 are then slid over themiddle layer 42. A heat shrinkable tube of, for example, fluorinatedethylene propylene, FEP, is then slid over the outer layer 44. The FEPis heated so as to deliver heat to the outer layer 44, and the outerlayer 44 then softens to encapsulate the wire 46. The FEP tube is thenremoved from the outer layer 44.

In one embodiment of the present invention, the outer diameter of theouter layer 44 of the outer assembly 14 is in the range of 0.03 to 0.040inches. The lumen 20 of the outer assembly 14 may have a diameterbetween 0.020 to 0.029 inches. In one embodiment, the lumen 20 of theouter assembly 14 may have a diameter of approximately 0.0285 inches.

As shown in FIGS. 5A and 5B, the inner assembly 16 is a tubularstructure having a multilayer wall formed of an inner layer 64, middlelayer 66, and outer layer 68. The inner layer 64 of the inner assembly16 is formed of a longitudinally continuous or segmented tubularelements. In embodiments in which the inner layer 64 of the innerassembly 16 is formed of longitudinally segmented tubular elements, theindividual segments may be fabricated from the same or differentmaterials and may be attached to one another by welding, fusing,adhering, melting, or other polymerizing or non-polymerizing methods, orcombinations thereof. The inner layer 64 of the inner assembly 16 isfabricated from one or more different polymeric materials, or,alternatively, the inner layer 64 of the outer assembly 14 is formed ofa single, non-segmented, etched polytetrafluoroethylene, PTFE, tube.While a variety of materials are contemplated for use in fabricating theinner layer 64 of the inner assembly 16, it is important to employ amaterial that has a higher melting temperature than the temperatureemployed to fuse or otherwise attach the outer layer 68 to the innerlayer 64 and middle layer 66 of the inner assembly 16. It is alsodesirable to employ a material that has a relatively low co-efficient offriction.

In one embodiment of the present invention, the middle layer 66 of theinner assembly 16 comprises a wire 70 wound in a coil-like form aroundthe outer surface 72 of the inner layer 64 of the inner assembly 16. Thewire 72 may be wound in a single layer from one end of the inner layer64 to the other or, alternatively, may be wound repeatedly from one endof the inner layer 64 to the other to form a multilayer coil-like form,as shown in FIG. 4A regarding wire 46 of the outer assembly 14. Inembodiments employing the middle layer 66 having a multilayeredcoil-like form, the different coils may be formed from a single ormultiple independent wires 72. The wire 72 may have a circular,rectangular, triangular, flattened, ribbon-like cross-sectional shape,or a combination thereof. The wire 72 may be fabricated from a varietyof metallic and/or polymeric materials, for example stainless steel. Thewire 72 may have a diameter that is variable or consistent along thelength of the wire 72. For example, the wire 72 may have a diameter ofapproximately 0.001 inches. It is also contemplated that the middlelayer 42 may be formed of a mesh or interweaving of one of more wires46.

The pitch of the winding of the wire 72 may be either consistent orvaried along the length of the inner layer 64 of the inner assembly 16.For example, a first proximal segment of the wire 72 winding may have apitch of approximately 0.003 inches, a second more distal segment mayhave a pitch of approximately 0.003 inches, and a third most distalsegment may have a pitch of approximately 0.001 inches.

As shown in FIGS. 2 and 5A, in one embodiment of the present invention,one or more marker bands 82A, 82B, and 82C are placed, for example, overthe wire 70 forming the middle layer 66 of the inner assembly 16. Themarker bands 82A, 82B, and 82C comprise a radiopaque material such asgold, platinum, or silver, and are used for determining the location ofthe balloon catheter 10 within a patient. In certain embodiments of thepresent invention the maker band 82A may be placed a distance L3proximate to a distal end 86 of the inner assembly 16. For example, thedistance L3 may be 5 millimeters. In one embodiment, instead of markerbands, marker coils may be used. In one embodiment, two sets of markercoils are used where one coil overlaps another to augment theradiopacity of the marker elements.

The marker bands 82B and 82C may be positioned further proximal of themarker band 82A so as to indicate or mark the proximal portion 24 andthe distal portion 28 of the balloon 18. It will be understood that theexact placement of the marker bands 82B and 82C relative to the distalend 86 of the inner assembly 16 will depend on the dimensions of theballoon 18 employed in the balloon catheter 10.

For example, in an embodiment employing a balloon 18 of 10 millimetersin length, a proximal end 84 of the marker band 82C is a distance L1from the distal end 86 of the inner assembly 16. For example, thedistance L1 may be approximately 19.5 millimeters. Opposite ends of themarker bands 82B and 82C are a distance L2 from one another. Forexample, the distance L2 may be 10 millimeters. In an embodimentemploying a balloon 18 of 20 millimeters in length, the distance L1 is,for example, approximately 29.5 millimeters, and the distance L2 is, forexample, 20 millimeters. In another embodiment, the marker band 82C maybe placed directly underneath the inflation plug 88.

In one embodiment of the present invention, the outer layer 68 of theinner assembly 16 comprises a longitudinally continuous or segmentedtubular element. Preferably the outer layer 68 of the inner assembly 16is formed of series of longitudinally segmented, non-heat shrinkable,tubular elements. The individual segments are fabricated from the sameor different materials and may be attached to one another by welding,fusing, adhering, melting, or other polymerizing or non-polymerizingmethods. Preferably, the outer layer 68 of the inner assembly 16 isfabricated from multiple different polymeric tubular segments. Forexample, a proximal segment 74 of the outer layer 68 of the innerassembly 16 may be formed of a tubular poly ether block amide such asPebax 63D. The proximal segment 74 has a length 75 of, for example,approximately 150 centimeters. A second more distal segment 76 may beformed of a tubular polyether block amide such as Pebax 45D. The secondmore distal segment 76 has a length 77 of, for example, approximately 10centimeters. A third more distal segment 78 may be formed of apolyolefin such as Plexar 3080. The third more distal segment 78 has alength 79 of, for example, approximately 2 millimeters. A distal mostsegment 80 may be formed of a polyolefin such as Engage 8003, and have alength 81 of, for example, approximately 5 centimeters.

The inner assembly 16 may be fabricated by first wrapping the wire 70around the inner layer 64 thereby forming the middle layer 66. Next, themarker bands 82A, 82B, and 82C are placed over or within the middlelayer 66, and the tubular segment or segments of the outer layer 68 arethen slid over the marker bands 82A, 82B, and 82C and the middle layer66. A heat shrinkable tube of, for example, fluorinated ethylenepropylene, FEP, is then slid over the outer layer 68. The FEP is heatedso as to deliver heat to the outer layer 68, thereby softening the outerlayer 68 so as to encapsulate the wire 70 forming the middle layer 66.The FEP tube is then removed from the outer layer 68.

In one embodiment of the present invention, the wire 70 forming themiddle layer 66 of the inner assembly 16 may terminate proximal of thedistal end 86 of the outer assembly 16. A tubular element 100 may beemployed in all or a portion of the length between the distal end 86 andthe point at which the wire 70 terminates. The tubular element 100 may,for example, be formed of a crosslinked polyolefin tube having a lengthof approximately 5 millimeters.

In one embodiment of the present invention, the outer diameter of theouter layer 68 of the inner assembly 16 is in the range of 0.015 to0.025 inches, and more preferably in the range of 0.020 to 0.0225inches.

As shown in FIGS. 2, 5A, and 5C, in one embodiment of the presentinvention, the inner assembly 16 may further comprise an inflation plug88. The inflation plug 88 is formed of a tubular segment of materialhaving a wall of either uniform or asymmetric thickness. In someembodiments, the inflation plug may have a durometer ranging between 18Ato 55D. The inflation plug 88 may, for example be formed of a poly etherblock amide such as Pebax 55D. The inflation plug may, for example, beapproximately 5 millimeters in length and a distal end 90 of theinflation plug 88 may, for example, be positioned approximately 4millimeters from the proximal end 84 of the marker band 82C. An outerdimension or diameter of the inflation plug 88 is large enough so thatthe inflation plug 88 may not completely pass into the lumen 20 of theouter assembly without significant force. The inflation plug 88 may beformed on the inner assembly 16 as described above regarding theformation of the outer layer 68 of the inner assembly 16.

As shown in FIG. 5C, the inflation plug 88 may comprise one or morepassages or channels 92 formed longitudinally along the length of theinflation plug. The channel 92 may be formed by placing a mandrellongitudinally along the outside surface of the inflation plug 88 priorto sliding the heat shrinkable tube of, for example, FEP over theinflation plug 88. When the FEP is heated so as to deliver heat to theinflation plug 88, the mandrel melts into the inflation tube thereby thechannel 92 within the inflation plug 88. The FEP tube is then removedfrom the inflation plug 88.

The inflation plug 88 functions, in part, to longitudinally lock theinner assembly 16 to the outer assembly 14 so as to prevent changes inthe length of the distal extension of the distal portion 30 of the innerassembly 16 relative to a distal end 98 of the outer assembly 14 due tothe inflation and orientation of the balloon 18 during a procedure. Thepassage or channel 92 formed in the plug 88 allows for fluidcommunication between the lumen 20 of the outer assembly and an interiorvolume of the balloon 18.

As shown in FIGS. 3, 5B, 5C, and 7 , the inner assembly 16 comprises aninner lumen 22. The lumen functions as a guidewire lumen forover-the-wire procedures. The lumen 22 of the inner assembly 16 may havea diameter of at least approximately 0.0165 inches. Accordingly, theballoon catheter 10 of the present invention may be used with guidewireshaving a larger diameter than the guidewires supplied with currentballoon catheters intended for use in neurological procedures. Forexample, the present balloon catheter 10 may be used with a guidewirehaving a diameter of 0.014 inches. This feature allows a physician tomore easily access a neuroanatomical target, such as an aneurysm, sincethe relatively larger guidewire provides more support for the ballooncatheter 10 over which to track.

Additionally, the guidewire may be removed from the lumen 22 afterplacement of the balloon catheter within a patient and the lumen 22 mayserve as a functional lumen for passage of additional medical devices orsubstances to the target location within the patient.

It will be understood that it is generally beneficial for the outerassembly 14 and the inner assembly 16 to be more flexible at theirdistal portions than their proximal portions. Furthermore, it iscontemplated that the distal portions of the outer assembly 14 and/orthe inner assembly 16 may be pre-shaped or operable to be shaped by aphysician prior to initiating a procedure using, for example, steamshaping techniques.

As shown in FIGS. 1 and 6 , the proximal portion 36 of the outerassembly 14 terminates distally of the proximal portion 38 of the innerassembly 16. Accordingly, the lumen 20 of the outer assembly is incommunication with the inflation port 32. FIGS. 1 and 6 also show thatthe proximal portion 38 of the inner assembly 16 extends proximallybeyond the proximal portion 36 of the outer assembly 14 and isassociated with the guidewire port 34 of the hub 12. Accordingly, thelumen 22 of the inner assembly and the guidewire port 34 of the hub 12together form a substantially continuous lumen through which a guidewireor other medical device may pass. The outer assembly 14 and the innerassembly 16 may be attached to the hub 12 by various methods, includingwelding, fusing, adhering, melting, or other polymerizing ornon-polymerizing method, or combinations thereof. It is noted that thisconfiguration of the hub 12 and association of the hub 12 with the outerassembly 14 and the inner assembly 16 advantageously provides for theisolation of the lumen 22 of the inner assembly 16 from the lumen 20 ofthe outer assembly 14. The isolation of these lumens and theirfunctionality serves, in part, to address many of the shortcomingsdescribed above regarding the current single lumen balloon cathetersintended for neurological procedures.

As shown in FIGS. 1 and 2 , the proximal portion 24 of the balloon 18 isassociated with the distal portion 26 of the outer assembly 14, and thedistal portion 28 of the balloon 18 is associated with the distalportion 30 of the inner assembly 16. The balloon 18 may be attached tothe distal portion 26 of the outer assembly 14 and the distal portion 30of the inner assembly 16 by various methods including welding, fusing,adhering, melting, or other polymerizing or non-polymerizing methods andcombinations thereof. In certain embodiments, the distal portion of theballoon 18 covers and extends to the distal end 86 of the inner assembly16. The balloon 18 may, for example, be formed of Polyblend 45A or otherpolymeric elastomeric material. The balloon 18 may have an outerdiameter of up to approximately 15 millimeters and a length in the rangeof 5 to 50 millimeters and, preferably a length in the range of 10 to 20millimeters.

As shown in FIG. 7 , in one embodiment of the present invention, one ormore air purge ports 94 are employed at the interface of the distalportion 30 of the inner assembly 16 and the distal portion 28 of theballoon 18. The air purge ports 94 are formed by placing one of moremandrels having diameters in the range of 0.0005 to 0.030 inches on theouter surface of the outer layer 68 of the inner assembly 16. Aninterior surface 96 of the balloon 18 is then attached over the mandrelsto the outer layer 68 of the inner assembly 16. After the balloon 18 isattached to the distal portion 30 of the inner assembly 16 the mandrelsare removed. Accordingly, flow paths large enough for the passage of gasand small enough to seal against the passage of liquids are formed.

The air purge ports 94 function to facilitate removal of air from thelumen 20 and balloon 18 prior to initiating a medical procedure. Withcurrent co-axial balloon catheters, it is very difficult to remove allof the air from the inflation/deflation lumen prior to initiating amedical procedure. Physicians typically must remove the air from aballoon catheter through several minutes of aspiration or suctionthrough the inflation/deflation lumen. Air that is not removed will showin images taken during the procedure and may obscure details that thephysician may otherwise need to observe in order to perform theprocedure.

In contrast, the air purge ports 94 of the present invention allow auser to more effectively and more efficiently remove air from the lumen20, the inflation/deflation lumen. In practice, prior to initiating theprocedure, a physician positions the distal end of the balloon catheter10 higher than the proximal end and then injects a balloon inflationmedium, such as contrast medium or saline, through the inflation port 32and associated lumen 20. As the inflation medium fills the lumen 20, airis forced out the air purge ports 94 until no air remains within thelumen 20 or balloon 18. The physician may repeat the process as neededto ensure that all air is removed from the lumen 20 of the outerassembly 14 and balloon 18.

In another embodiment of the present invention, as shown in FIGS. 8 and9 , the above described functionality of the inflation ports 32 isenhanced by employing one or more de-airing channels 102. The de-airingchannel 102 is formed in the outer layer 68 of the inner assembly 16. Ata minimum, the de-airing channel 102 initiates longitudinallyapproximate the distal end 90 of the inflation plug 88 and continuesuninterruptedly to approximately a proximate end of the air purge port94. The length of the de-airing channel 102 may extend to or overlapwith the distal end 90 of the inflation plug 88 and/or the proximate endof the air purge port 94. The de-airing channel 102 may be eitherradially aligned or radially off set with the channel 92 of theinflation plug 88 and/or the air purge port 94 relative to an axisthrough the lumen 22 of the inner assembly 16.

The de-airing channel 102 is formed by placing one of more mandrelshaving diameters in the range of 0.001 to 0.030 inches between the outerlayer 68 of the inner assembly 16 and the heat shrinkable tube and thenheating the heat shrinkable tube as described above. In certainembodiments, the de-airing channel 102 is radially aligned with the airpurge port 94 and/or with the channel 92 formed in the inflation plug88. For example, FIG. 9 shows an embodiment in which the de-airingchannel 102 is radially aligned with the air purge port 94. Thede-airing channel 102 and the air purge port 94 each form a portion of aunified channel. In embodiments in which the de-airing channel 102 isradially aligned with the air purge port 94 and/or with the channel 92formed in the inflation plug 88, the de-airing channel 102 may extendlongitudinally the length of the air purge port 94 and/or may extendlongitudinally into or proximately beyond the channel 92 formed in theinflation plug 88.

The de-airing channel 102 helps ensure that a fluid and air flow path ismaintained unobstructed between the exterior surface of the innerassembly 16 and the interior surface 96 of the balloon 18. Because theballoon 18 may be closely form fitted over the inner assembly 16 whenthe balloon is not inflated, absent a de-airing channel 102, it may notalways be possible to purge air from lumen 20 of the outer assembly 14without inflating the balloon 18. Hence, the de-airing channel 102provides a recess or unobstructed channel on the exterior surface of theinner assembly 16 that allows the passage of air and fluid between thedeflated balloon and the exterior surface of the inner assembly 16.Hence, air may be purged from the balloon catheter 10 without inflatingof the balloon 18.

It is also contemplated that the de-airing channel 102 may take the formof one or more spiral channels or grooves, spiral ridges, and/orlongitudinal ridges on the exterior surface of the inner assembly 16.The de-airing channel 102 may also take the form of one or more smalltubular elements bonded to the exterior surface of the inner assembly16.

In the following embodiments shown in FIGS. 10-18 , the purge port 94 islocated at a distal interior portion of an inflatable portion of theballoon 18 and is intended to represent an opening or an area of anopening and the de-airing channel 102 links the distal purge port 94 toan exterior of the distal end of the balloon catheter. Accordingly, airis conveyed distally from purge port 94 through de-airing channel 102and out of the distal end of the balloon catheter. The purge port 94 istherefore the proximal entry point for air, where the air is thenconveyed distally through de-airing channel 102. All the purging of airfrom the interior of the balloon is performed at the distal portion ofthe balloon catheter. The inflation lumen remains located proximal tothe balloon 18; therefore, the balloon 18 is inflated from the proximalend while all the purging is performed at the distal section of theballoon 18. As described in the following embodiments, de-airing channel102 is initially open to purge air from the balloon 18 during a first,preparation stage; de-airing channel 102 is later sealed in a second,operational state to prevent the balloon from leaking when the balloonis used in an inflated state during an interventional procedure. Inthese embodiments purge port 94 represents a proximal opening, locatedwithin the balloon, into de-airing channel 102. An opposite, distal endof the de-airing channel 102 is located at the distal end of the ballooncatheter.

One embodiment of the present invention includes a swellable materialalong with the previously described purge port and the de-airing channelarrangement. The swellable material swells in response to exposure tocertain materials, such as liquids, and thereby closes the de-airingchannel to block passage of liquids. It may be desirable to selectivelyallow the de-airing channel to initially be open to purge air, but tothen close upon exposure to liquid (such as saline or contrast agent) toprevent liquid escaping from the balloon in order to keep the ballooninflated over time. In one example, the user flushes the system withcontrast agent to expel air and prepare the balloon for use. Contrastagent is also used to inflate the balloon during use. Once the air ispurged out of de-airing channel, the de-airing channel closes uponexposure to contrast agent to prevent contrast agent from later escapingonce additional contrast agent is later introduced to inflate theballoon (e.g. once the balloon is later inflated in the body during theinterventional procedure).

The swellable material can be used either on or over a portion ofde-airing channel or can be placed adjacent to de-airing channel, forexample near purge port 94. A hydrophilic material will swell uponexposure to liquid (e.g. saline or contrast agent) and closes thede-airing channel once the section of the de-airing channel containingthe hydrophilic swellable material is exposed to liquid. The de-airingchannel, therefore, stays open as air is expelled through the port;however, once de-airing channel contacts the liquid (e.g., in asituation where the air is almost completely flushed from theballoon/balloon catheter and now liquid is being expelled), de-airingchannel will swell causing the internal passage to contract, blockingthe liquid from being expelled. Various hydrophilic materials such asrubber or hydrogel can be used as the swellable material.

The swellable material may be located adjacent de-airing channel or mayphysically comprise a particular section (e.g., the distal section) ofde-airing channel. FIG. 10 shows such a system, utilizing a swellablematerial adjacent the de-airing channel 102. Specifically, FIG. 10illustrates a cross sectional view of an embodiment of the presentballoon catheter near the distal end of the balloon 18, where thede-airing channel 102 spans a distal, non-inflatable portion of theballoon 18. A swellable layer 110 is located under the de-airing channel102, in addition to the optional additional liner layers 112, 114, 116,which can be located between the guidewire lumen 16 and the swellablelayer 110. Alternatively, the swellable material can be used with any ofthe prior purge/de-airing system embodiments.

Alternative configurations may position the swellable material on adistal section of de-airing channel, thereby allowing the de-airingchannel to contract upon exposure to liquid instead of having anadjacent surface compressing the de-airing channel. Alternatively, theswellable material can be utilized over the entire length of de-airingchannel. Alternatively, the swellable material may be placed at theproximal end of de-airing channel or even at the purge port.

In another embodiment, the de-airing channel is collapsible. De-airingchannel has a first, open configuration but collapses to adopt a second,closed configuration in response to a stimulus such as aspiration or avacuum. The user prepares the balloon by introducing an agent (e.g.,saline or contrast agent) to clear the air from the balloon. Next, theuser introduces a vacuum or aspiration source which causes the de-airingchannel to collapse and thereby shut. Later in the procedure, when theballoon is positioned in the body, the de-airing channel will remainsealed and the inflation media (e.g. contrast agent) will not escape,preventing the balloon from deflating over time.

A soft, tacky, and collapsible material can be used to create thede-airing channel 102 to enable the channel to easily collapse. Anelliptical cross sectional shape may be desirable for such a system sothat the minor axis of the ellipse requires only minor movement tocollapse completely, although a more rounded shape may also be usedwhere the de-airing channel walls are composed of a relatively weakpolymer material that allows easy collapse. Additional cross sectionalshapes, such as a “D” or a “C” shape, are also possible. In theseexample shapes, the flat side of the “D” shape or the open portion ofthe “C” shape can be oriented such that they are either facing adirection toward the guidewire lumen 16 or facing away from theguidewire lumen 16 (e.g., facing “downward” or “upward” in the examplecross section of FIG. 10 ).

In one example, the entire length of de-airing channel is collapsible.In another example, only a section of de-airing channel is collapsible.In another example, only the purge port (which links to the de-airingchannel) is collapsible. This collapsible section may be accomplished bya variety of methods, such as creating a weakened wall region in asection of the channel, thus allowing that section to easily constrict.FIGS. 11 and 12 show a cross-section of a collapsible de-airing channelin which the channel has a first open configuration 102 a when thechannel is open to purge the system, and the channel subsequently adoptsa second closed configuration 102 b once vacuum or aspiration is used toclose all of the channel or a weakened section of the channel.

In another embodiment, the de-airing channel includes a restrictingmember positioned at or past the proximal end of the de-airing channelto block fluid flow at the proximal part of the de-airing channel oncethe balloon has been collapsed over the de-airing channel, therebypreventing over-aspiration. This restricting member may be a wall regionhaving an increased thickness and located at the proximal end of thede-airing channel to block the channel lumen. This restricting membercan also be described as a bump or protruding region which blocks accessto the purge port and the de-airing channel. In operation, the useraspirates to deflate the balloon, however over-aspiration (the conditionwhere suction or aspiration continues after the balloon is fullydeflated) is undesirable since blood could be introduced into theballoon catheter. The bump seals de-airing channel preventingover-aspiration.

This configuration is shown in FIGS. 13 and 14 , where the right siderepresents the distal end of the balloon and the de-airing channel 102spans from a distal, interior, inflatable section of the balloon 18 tothe distal tip or end of the balloon catheter. In FIG. 13 , the balloonis inflated and a bump 118 does not impede fluid flow since the balloon18 is inflated and there is space for the fluid to pass. In FIG. 14 theballoon 18 is deflated, such as after the user has aspirated the balloon18 to deflate it. In the deflated state, the bump 118 blocks the fluidflow path to the purge port 94 and the de-airing channel 102, so oncethe balloon 18 is completely deflated, further aspiration or suction isnot possible.

In another embodiment shown in FIGS. 15 and 16 , the de-airing channel102 seals itself when the balloon 18 is fully inflated, to prevent anyleakage from the balloon 18. In this embodiment, the distal section ofthe de-airing channel 102 is integral with the distal portion of theballoon wall. In other words, the wall of the balloon 18 contains alumen which defines the de-airing channel, where the proximal lumenopening into de-airing channel 102 can be considered the purge port 94.This may be made in a number of ways, for example, the de-airing channel102 may be first constructed utilizing a mandrel and then the ballooncan be built over the de-airing channel 102 passage so that thede-airing channel 102 is incorporated into the distal section of theballoon 18; meaning the distal portion of the balloon 18 will includethe de-airing channel 102 incorporated into the wall of balloon 18.

Alternately, the balloon can be built and then a mandrel can be placedwithin the balloon to form a lumen, where said lumen would define thede-airing channel. The wall of the balloon will stretch and will thin asthe balloon inflates. This stretching and thinning action will compressa portion of the de-airing channel, which is incorporated into theballoon wall, causing the de-airing channel to close. Thus, when theballoon is fully inflated, the de-airing channel will close preventingany leakage. In an alternative configuration, a reinforcing bandattached to the balloon may also be utilized to create a choke point onthe distal section of the balloon. As the balloon expands, the bandapplies force on the section of the de-airing channel directly under theband since the distal de-airing channel is integrated into the balloonwall, which creates a choking point and closes a section of thede-airing channel.

Similar to the compressible de-airing channel embodiment above whichutilizes an elliptical, or C-shaped, or D-shaped cross sectionalde-airing channel shape to aid the self-closing of the de-airingchannel, this embodiment may also utilize these channel shapes tofurther enable easier closing of the channel. The bump feature of FIGS.13 and 14 may also be used to create a system that would prevent balloonleakage when the balloon is inflated as well as prevent over-aspirationonce the balloon is deflated. This is presented in FIGS. 15 and 16 ,where de-airing channel 102 is integral with the balloon 18 wall. In oneexample, the balloon 18 utilizes liners 120, 122 which connect to partof the de-airing channel 102. As the balloon 18 expands, the linerscompress against de-airing channel 102 causing the channel to close - asshown in FIG. 15 , where the proximal section of the de-airing channel102 tapers down to the point it is completely shut. When the balloon 18is deflated as shown in FIG. 16 , the de-airing channel 102 opens andthe bump 118 prevents over-aspiration.

FIGS. 17 and 18 show another embodiment of a purging system used in aballoon catheter according to one embodiments of the present inventionthat utilizes a membrane which allows passage of air/gas from theballoon while not allowing passage of liquid. The inflation lumen isused to initially inject a liquid inflation media (e.g. contrast agent)to purge residual gas from the balloon and from the balloon catheterbefore placing the balloon within the patient’s body. The catheterincludes the purge port 94 which includes a permeable membrane 128 thatallows passage of gas but not liquid from the balloon - allowing air toescape while retaining the liquid inflation media. The purge port islinked to a de-airing channel 102 which is in communication with an areaexternal to the balloon 18, such that the air is conveyed from the purgeport 94 through the de-airing channel 102 and externally purged from thecatheter (shown by arrows). Since the membrane 128 blocks liquid fromescaping, the balloon 18 resists leaking so that it can maintain itsproper inflated shape of the balloon 18 once the balloon 18 is inflatedwithin the patient’s vasculature system.

FIG. 17 shows a distal section of a balloon catheter which includes aballoon 126 and a purging system. The purging system utilizes the purgeport 94 which includes a membrane 128, and the de-airing channel 102linked to the purge port 94. The balloon 126 is proximally bonded to theinflation lumen so that inflation media (e.g. contrast agent) deliveredthrough the inflation lumen inflates the balloon 126. The balloon 126 isdistally bonded to the distal portion 30 of the inner assembly/guidewirelumen 16 - similar to the configuration shown in FIG. 2 . The permeablemembrane 128 is placed under the balloon 126. the membrane 128 containspores which are sized to allow the passage of air/gasses but not liquid.

In one example, the membrane 128 is an ePTFE layer with a thickness ofabout 0.0006″-0.0007″ and a pore size of about 0.4-0.6 microns. Thepolymer can be treated in a number of different ways to impart pores ofan appropriate size to create the membrane. In one preferred embodiment,the polymer is heat treated in order to make the polymer stretchable,the polymer is then stretched to create various pores therein, thenreheated to lock in the particular stretched shape. In anotherembodiment, a chemical is utilized and the chemical eats through thepolymer in order to create the membrane. In another embodiment, ane-spun process can be used to create a spider-web like structure withappropriately-sized pores. In another embodiment, the membrane is aporous foam material.

As shown in FIGS. 17 and 18 , a ringed radiopaque (e.g. platinum) markerband 130 is placed under only a proximal portion of the membrane 128, alayer 132, for example a polymer layer, sits under the marker band 130,and a liner 134, for example a PTFE liner, sits under the polymer layer132. The portion of the membrane 128 without the marker band 130reinforcement-layer defines the purge port 94, while the de-airingchannel 102 sits under the more distal portion of the membrane 128 andprovides a communication path for the air to an exterior of the distalend of the balloon catheter. The membrane 128 separates balloon 126 andthe de-airing channel 102 and helps define the proximal purge-port 94which acts as an intermediary allowing passage of gas/air but not thepassage of liquid, for example the balloon inflation liquid as discussedearlier. The de-airing channel 102 communicates proximally with purgeport 94 and distally with an area external of the balloon, so airpassing through the membrane 128 of the purge port 94 is conveyedthrough the de-airing channel 102 and displaced externally, as indicatedby the flow arrows shown in FIG. 17 . Since the balloon 126 connects tothe inner assembly/guidewire lumen, these elements all comprise thedistal part of the inner assembly/guidewire lumen. FIG. 18 is a crosssectional view along line F shown in FIG. 17 of the distal part of theinner assembly/guidewire lumen showing how all the layers sit relativeto each other, when the balloon 126 is in a deflated state. The layer134 forms the inner base liner of the guidewire lumen and the balloon126 forms a top exterior layer of the distal portion of the ballooncatheter, a distal most portion of balloon 126 being non-inflatable.

In order to create the purge port 94 and the de-airing channel 102, inone embodiment of the present invention, a 0.001″-0.005″ thick mandrelis placed within the polymeric layer 132. The mandrel is then removedleaving a gapped section. The membrane 128 is placed over the gap; themembrane 128, as discussed earlier, has a specific permeability to allowgas molecules but not allow liquids through, therefore the liquid willbe retained in the balloon while the gasses escape. The membrane 128sits over a proximal section of the de-airing channel 102 defining thepurge port 94. Gas passes through the purge port 94, through thede-airing channel 102, and out of the distal end of the ballooncatheter.

The function of the purge port 94 and membrane 128 in the embodimentshown in FIGS. 17 and 18 is to provide a selective escape path for airbut not liquid so that air can escape the balloon 126. The air is thenexpelled from the balloon 126 via the purge port 94, through thede-airing channel 102 and then out of the distal end of the ballooncatheter. To this end, the purge port 94 includes a membrane layer 128to selectively allow the passage of air but not liquid. As shown in FIG.17 , the membrane 128 spans the entire distal section of the ballooncatheter, however the distal part of the balloon 126 is directly bondedto the membrane 128. Since the membrane 128 is directly bonded to theballoon 126, this part of the balloon 126 cannot inflate or deflate.Therefore, the air will only pass out of the balloon 126 through thepurge port 94, which is located next to a non-bonded section of theballoon (e.g. a section of the balloon 126 which inflates and deflates).

The method for prepping and using the balloon involves injecting aliquid, such as contrast agent, through the inflation lumen of theballoon catheter to flush out any residual air/gas in the balloon 126.The gas permeates through the purge port 94 and exits the de-airingchannel 102 out the distal tip or end of the balloon catheter. Theliquid is retained in the balloon, and the user employs aspiration orsuction to withdraw the liquid back through the inflation lumen todeflate the balloon 126. Once the balloon catheter is prepped and theresidual gases are purged, the balloon catheter is placed into thevasculature and inflated by, again, injecting liquid through theinflation lumen. The balloon 126 will remain inflated since the membrane128 ensures liquid cannot escape out of the balloon through the purgeport 94 and de-airing channel 102.

The embodiments shown and described in FIGS. 17 and 18 can be used withother purge system embodiments shown and described in other figures andin other parts of this application. For instance, FIGS. 13 and 14utilized a bump 118 to prevent over-aspiration of the balloon. The bump118 can also be utilized by placing the bump 118 over a portion of themembrane 128, or by placing the bump 118 at a more proximal location,proximal of the membrane 128 to prevent over-aspiration of the balloon.

In another embodiment, a diameter of the lumen 20 of the outer assembly14 is tapered from the proximal to the distal end of the catheter, asshown in FIG. 19 a . This taper will result in a tapered inflationlumen. Position 98 indicated by the dashed line shown in FIG. 19 a issimilar to the distal end of the outer assembly indicated by position 98in FIG. 2 . Inner assembly 16 employs the guidewire lumen of the earlierfigures. In one example, the lumen diameter 20 a at position 98 is inthe range of 0.02″ - 0.03″, and a more specific example is 0.0293″. Inone example, the lumen diameter 20 b at the most proximal position ofthe balloon catheter is in the range of 0.03″-0.035″, a more specificexample is 0.0305″.

The tapered lumen 20 can be produced by utilizing a tapered mandrel toform the outer assembly 14. The tapered mandrel would result in atapered inner diameter/lumen 20. The use of a taper means the proximalportion of the balloon catheter has a thinner structural layer andlarger inflation volume than the more distal portion of the ballooncatheter, which has a thicker structural layer and smaller inflationarea. This difference in inflation volume is particularly beneficial fordeflation of the balloon, where the higher proximal volume allows forgreater suction pressure than would be otherwise possible with aconsistent volumetric profile throughout lumen 20.

FIG. 19 b illustrates another example of a tapered inflation lumen 21.Unlike the example in FIG. 19 a , the inflation lumen 21 utilizes anon-linear taper that is curved from a larger diameter region 21 b to asmaller diameter region 21 a. Other shapes are also possible.Preferably, the tapered shape lacks sharp edges to prevent any areaswhere air can get caught and create eddies or turbulence which wouldnegatively affect the deflation time. The inflation lumen shape can beformed by utilizing a shaped mandrel, and thus various shapes arecontemplated by utilizing an appropriately shaped mandrel.

Similar to the earlier embodiments described, the tapered inner lumen 21can comprise a polymer with a higher melt temperature than outer layersof the outer assembly 14. The outer assembly 14 employing the taperedinner lumen 21 can also include a metallic reinforcement layer.

In another embodiment, a tapered inflation lumen is utilized, but thetaper is only utilized on a small portion of the lumen. Balloons andballoon catheters used in the neurovasculature typically have arelatively small size due to the smaller blood vessels in this region ofthe body. A taper is desirable in order to augment suction pressure;however, a continual taper is difficult to achieve given the limitedvolumetric capacity of the inflation lumen given the smaller size of thecatheter due to the smaller neurovasculature blood vessels. Thus, ataper may be used in a limited portion of the inflation lumen locatednear the balloon element. In one example the overall inflation lumenlength is 60-70 inches, and the taper exists in about 1-6 inches of theinflation lumen length. In one example, since the taper is limited to asmall section of the lumen instead of being distributed throughout thelumen, the transition from the smaller diameter to larger diametersection will be fairly significant.

FIG. 19 c shows a localized taper which could be particularly useful insome embodiments. It is generally desirable for a balloon catheter tohave a large proximal section and a small distal section, especially inthe neurovasculature space. A large proximal section will maximize pushforce and accommodate a large inflation lumen 20 to speed up inflationand aspiration of the balloon 18. A small distal balloon cathetersection allows for a smaller balloon size which is useful to allowplacement in the smaller vessels in the neurovasculature - in addition,a smaller distal section will also augment flexibility and navigabilityof the balloon catheter in the smaller neurovascular blood vessels. FIG.19 c utilizes a relatively consistent larger diameter on the proximalsection, a relatively consistent smaller diameter on the distal sectionof the catheter, and a short taper 15 b in between the two sections,this relatively short tapered section allows a quick transition betweena large proximal section and a small distal section which includes theballoon 18. This taper can exist and match both on the inner assembly 16(see inner taper 15 a) and outer assembly 14 (see outer taper 15 b).

This design also offers some advantages in manufacturing the ballooncatheter, since the inner assembly 16 and the outer assembly 14 can beseparately manufactured and placed over each other, where one can simplymatch up the tapers 15 a and 15 b to ensure the inner assembly 16 andouter assembly 14 are appropriately placed relative to each other, andthe inner assembly 16 and the outer assembly 14 can then be bondedtogether to create the integral balloon catheter. In one example, thesection proximal of the taper 15 b of the outer assembly 14 has, forexample, an outer diameter of about 0.034″-0.038″, and the sectionproximal the taper 15 a of the inner assembly 16 has, for example, aninner diameter of about 0.015″-0.020″. The section distal of the taper15 b of the outer assembly 14 has, for example, an outer diameter ofabout 0.020″-0.037″, and the section distal the taper 15 a of the innerassembly 16 has, for example, an inner diameter of about 0.001 “-0.020”.The tapered sections 15 a and 15 b have a length of about 2-3centimeters, and the section of the balloon catheter distal of thetapered sections 15 a and 15 b extend distally for about 15-20centimeters . The section of the balloon catheter proximal of thetapered sections extends for the rest of the length of the catheter,which is about 140 cm.

In another embodiment, both the guidewire lumen 22 and inflation lumen20 utilize a taper. In one embodiment, the tapers utilized on bothlumens extend throughout a substantial length, respectively, on both theguidewire and inflation lumens. In another embodiment, the tapers arepresent through only a small portion, respectively, of each of theguidewire and inflation lumens (e.g. about 1″-6″ of overall length). Inone example where both guidewire lumen 22 and inflation lumen 20 utilizea taper, the guidewire lumen 22 has a distal section inner diameter(e.g. distal of the taper) of about 0.01-0.015 inches, and a proximalsection diameter (e.g. proximal of the taper) of about 0.015 inches. Theinflation lumen 20 has a distal section inner diameter (i.e. distal ofthe taper) of about 0.023 inches and a proximal section diameter (i.e.proximal to the taper) of about 0.027 inches.

Proper delivery of the appropriate amount of balloon inflation media(e.g. contrast agent) is important, especially in the neurovascularspace where smaller balloons are used. Neurovascular balloons areparticularly small and can be filled with a small amount of inflationfluid (e.g. 0.01-0.02 milliliters), so it is very easy to underfill orover-fill a balloon given the limited balloon volume. Normally, a userdepresses a syringe to expel inflation fluid from a syringe, but it isdifficult to get precise dosing this way. FIGS. 20 a-22 e show a metereddispensing system utilizing a metered controller to obtain precise andproper metered dispensing of inflation media.

FIGS. 20 a-2 d illustrate one embodiment of a metered dispensing systemwhich includes a metered controller 140 which can be used with a syringe144 to deliver precise, metered doses of an inflation fluid (e.g.contrast liquid) from the syringe 144. FIG. 20 a shows an expanded viewof a dispensing system including a metered controller 140 which can beused on a syringe to provide precise metered dosing. The meteredcontroller 140 includes clip 142 so the controller 142 can affix to aproximal flange 146 of the syringe 144. A plunger 148 passes through alumen of the metered controller 140 and into the syringe 144. Distaldisplacement of the plunger 148 will expel fluid from the syringe 144.

FIG. 20 b shows the elements of FIG. 20 a mated together in an assembledview. The metered controller 140 includes a cap 150 which is in threadedengagement with a top piece 160 of the controller 140 so that the cap150 can be tightened to the controller 140. The metered controller 140includes a lumen which accommodates or receives the plunger 148. Theclip 142 engages with the syringe proximal flange 146 so that thecontroller 140 and syringe 144 are connected. A flexible compressionpiece 158, for example a silicon washer, shown in FIG. 20 e , sitsaround the plunger 150 within the metered controller 140 between the cap150 and the top piece 160. When the cap 150 is tightened relative to thetop piece 160, the cap 150 compresses the compression piece 158 againstthe top piece 160, and the compression piece 158 engages and locks theplunger 148 thereby preventing free displacement of the plunger 144relative to the cap 150 and top piece 160. The cap/compressionpiece/plunger grip mechanism can be thought of as a Tuohy-Borst system.

The metered controller 140 includes a rotational interface to allowmetered dispensing. The rotational interface is shown in FIGS. 20 c-20 d. The controller 140 includes the top piece 160 which includes the cap150 and a bottom piece 162 that is in threaded engagement with an end ofthe top piece opposite the cap 150. The top piece 160 is rotatable withrespect to the bottom piece 162 and doing so will displace plunger 148relative to the bottom piece 162 and, hence, relative to the syringe148. The top piece 160 includes a protruding element 152, and the bottompiece 162 includes a complementary groove 154. There are four grooves154 around the circumference of the bottom piece 162. The user canrotate the top half of the controller, i.e. the top piece 160 and thecap 150, so that the protruding element 152 is aligned with the groove154 such that the protruding element 152 sits within the groove 154.When alignment of the protruding element 152 and the groove 154 occurs,a “click” or similar audible feedback will occur. Alternatively stated,the portions of the bottom piece 162 between the grooves 154 may deflectover the rotating protruding element 152 (shown in FIG. 20 c ) andreturn to a non-or less deflected state when the protruding element 152is positioned within the groove 154 (shown in FIG. 20 d ). Each “click”corresponds to a particular metered dosing, for instance one click cancorrespond to a precise displacement of the plunger 148 resulting in0.01 ml or 0.02 ml of inflation fluid being delivered.

For a neurovascular balloon, typically 0.02 ml of inflation fluid (e.g.contrast agent) is sufficient to fill the balloon. Therefore, one click(if each click delivers 0.02 ml) or two clicks (if each click delivers0.01 ml) will be sufficient to fill the balloon. The controller 140 canfurther include numbering and a dispensing indicator (for example, anumber and a bar next to the number) so the use can tell how much fluidhas been delivered. Using the cap 152 and compression piece 158 to lockplunger 148, as discussed above, is important so that the rotation ofthe controller is then used to displace the plunger in a controlledmanner. The metered controller can be designed in different ways, forinstance more or fewer grooves 154 can be included to allow more or lessdispensing iterations.

FIG. 20 e is an expanded assembly view of the metered controller andmetered dispensing system. Syringe 144 includes an interface 156 adaptedto mate with a catheter hub to deliver the syringe contents through thecatheter. The metered controller 140 includes the bottom piece 162 andthe top piece 160. A distal portion of the top piece 160 includesthreads so that the top piece 160 and the bottom piece 162 can beengaged with each other and tighten with respect to each other when toppiece 160 is rotated by the user. At an opposite, proximal portion ofthe top piece 160 and the cap 150 are mated together using a threadedengaging mechanism and the compression piece 158 is disposedtherebetween and used to lock to plunger 148 in the Touhy-Borst typeengagement system described earlier.

FIGS. 21 a and 21 b show an alternative embodiment of the meteredcontroller shown in FIGS. 20 a and 20 e . In this embodiment, a meteredcontroller 140 b comprises a top piece 160 a and a bottom piece 162 b,except here the bottom piece 162 b has threads to mate with the toppiece 160 b such that the top piece mates over the bottom piece. Thisembodiment would still utilize the audible interface, so the top piecewould have a protruding element which contacts a groove on the bottompiece - however unlike the other embodiments, the protruding piece wouldsit over the groove and thus latch into the groove when the top piece160 a of the controller 140 b is rotated by the user relative to thebottom piece 162 b. The controller 140 b further employs a cap 150 b anda compression piece 158 b similar to that described relative to theembodiment shown in FIGS. 20 a-20 e .

FIGS. 22 a and 22 b show an alternative embodiment of a meteredcontroller according to the present invention. Like the controller ofFIGS. 21 a and 21 b , a top piece 160 c sits over a bottom piece 162 cwhere the bottom piece has threads to accommodate the top piece. Whereasthe previous embodiments utilized a cap which is tightened to lock acompression piece to the plunger, here a clamp 170 is used and the clamp170 tightens such that it is locked with respect to the plunger 148. Thetop piece 160 c of metered controller 140 c includes a recess whichaccommodates the clamp 170. Rotating the top half of the controller willrotate the plunger since the clamp, which is housed by the top piece, islocked to the syringe. The top piece 160 c has a protruding piece whichmates with a corresponding groove on the bottom piece to produce anaudible click at selected intervals, like in the previous embodiments.

In another alternative embodiment, the system of FIGS. 20 a-20 e , whichutilizes a top piece 160 received by a bottom piece 158, could utilize aclamp 170 instead of the compression piece to lock to the syringeplunger. In this embodiment, the top piece would accommodate the clamp,like how the top piece accommodates clamp 170 in FIGS. 22 a and 22 b .

In one preferred embodiment, the metered controller 140-140 c anddispensing system shown in FIGS. 20 a and 22 b can be used as part of abroader balloon catheter purging and delivery system, used with thepurge port/membrane concepts of any of the embodiments described above,for example with the embodiments of FIGS. 17 and 18 . The membrane, asdiscussed earlier, selectively allows passage of gas but not liquid topurge gas from a balloon. The metered controller/metered dispensingsystem of FIGS. 20 a-22 b will allow controlled dispensing of a preciseamount of inflation fluid (e.g. contrast agent). Since the membraneprevents passage of liquid, the inflation fluid will be retained withinthe balloon ensuring the balloon can maintain its proper inflated shapeafter the balloon is inflated.

It is contemplated that any of the embodiments herein described may beemployed individually or in combination with any other embodimentsherein described.

It is noted that while the present invention has been described withrespect to neurological procedures, it is contemplated that certainfeatures of the present balloon catheter also address needs innon-neurological fields.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. (canceled)
 2. A balloon catheter system,comprising: an outer tubular assembly comprising an inflation lumen; aballoon, wherein a proximal portion of the balloon is affixed to theouter tubular assembly; an inner tubular assembly, wherein a distalportion of the balloon is affixed to the inner tubular assembly; whereinthe inner tubular assembly includes a purge port in fluid communicationwith an interior of the balloon, the purge port comprising agas-permeable membrane that restricts passage of liquid through themembrane; and a de-airing channel in fluid communication with the purgeport through which gas expelled from the balloon may exit the ballooncatheter system.
 3. The balloon catheter system of claim 2, wherein themembrane comprises pores sized to accommodate gas passage but not liquidpassage.
 4. The balloon catheter system of claim 2, wherein the innertubular assembly comprises a guidewire port.
 5. The balloon cathetersystem of claim 2, wherein the inner tubular assembly is coaxiallyinserted within a lumen of the outer tubular assembly.
 6. The ballooncatheter system of claim 2, wherein the de-airing channel allows passageof gas out from a distal end of the inner tubular assembly.
 7. Theballoon catheter system of claim 2, wherein the membrane is adjacent tothe balloon.
 8. The balloon catheter system of claim 2, wherein theballoon is deflated when suction is applied through the inflation lumen.9. The balloon catheter system of claim 2, wherein the de-airing channelis located between the membrane and a structural layer of the innertubular assembly.
 10. The balloon catheter system of claim 2, wherein adistal portion of the balloon is bonded to the membrane.
 11. The ballooncatheter system of claim 10, further comprising a radiopaque marker bandproximally adjacent the de-airing channel.
 12. The balloon cathetersystem of claim 2, further comprising a syringe including an inflationliquid, a syringe plunger, and a metered controller that actuates thesyringe plunger to expel a metered dose of the inflation liquid from thesyringe to the inflation lumen.
 13. The balloon catheter system of claim12, wherein the metered controller comprises a signal corresponding tothe metered dose of the inflation liquid.
 14. The balloon cathetersystem of claim 12, wherein a portion of the metered controller rotatesto deliver the metered dose of the inflation liquid from the syringe.15. The balloon catheter system of claim 12, wherein the meteredcontroller is connected to a syringe flange at a first end and thesyringe plunger at a second end.
 16. The balloon catheter system ofclaim 12, wherein the metered controller comprises a protruding elementand a groove that mate when the metered dose of inflation liquid hasbeen dispensed.
 17. The balloon catheter system of claim 2, wherein thepurge port and the de-airing channel comprise a gap formed from theinner tubular assembly.
 18. The balloon catheter system of claim 17,further comprising a distal, non-inflatable portion of the balloonbonded at a distal end of the inner tubular assembly and over thede-airing channel.
 19. The balloon catheter system of claim 18, whereinthe membrane spans an entire distal section of the inner tubularassembly.
 20. A balloon catheter system, comprising: an outer tubularassembly comprising an inflation lumen; a balloon, wherein a proximalportion of the balloon is affixed to the outer tubular assembly; whereinan inflation fluid is delivered to the balloon through the inflationlumen; an inner tubular assembly, wherein a distal portion of theballoon is affixed to the inner tubular assembly; wherein the innertubular assembly includes a purge port in fluid communication with aninterior of the balloon, the purge port comprising a gas-permeablemembrane that restricts passage of liquid through the membrane, whereinthe balloon maintains an inflated shape after the balloon is inflated;and a de-airing channel in fluid communication with the purge port andin fluid communication with a space external to the balloon cathetersystem.
 21. A balloon catheter system, comprising: an outer tubularassembly comprising an inflation lumen; an inflation means, wherein aproximal portion of the inflation means is affixed to the outer tubularassembly; an inner tubular assembly, wherein a distal portion of theinflation means is affixed to the inner tubular assembly; wherein theinner tubular assembly includes a purge port in fluid communication withan interior of the inflation means, the purge port comprising agas-permeable membrane that restricts passage of liquid through themembrane; and a de-airing means in fluid communication with the purgeport and in fluid communication with a space external to the ballooncatheter system.